The present invention relates to a lighting system for use in a vehicle cabin.
In a cabin of an automotive vehicle, a lamp such as a reading lamp of the spot lamp type or a room lamp provides light when a driver or a passenger performs a visual work such as a reading in the dark or at night.
Generally, the lamp is arranged to a roof at its center portion (or in the vicinity of the center portion). For providing light in the cabin, the lamp is constructed in part or in its entirety by a material such as a resin having a diffuse transmission characteristic (see, for example, JP 54-3759).
As a result, the roof has a relatively light area in the vicinity of the lamp, and a relatively dark area at its portion distant from the lamp or its peripheral portion.
On the other hand, the lamp, which is mounted to the roof directly or indirectly through a reinforcing member, etc., often protrudes from the roof.
Problems faced in the known lighting system for use in a vehicle cabin are as follows:
With only the reading lamp turned on, an object of visual work is clearly illuminated in a spot manner while the environment is in full darkness. It is known that when a contrast of luminance is striking in such a manner, the driver or the passenger continuously moves his eyes in all directions during a reading, resulting in eyestrain. Additionally, the reading lamp clearly illuminates not only the object of visual work, but a face of the driver or the passenger who is reading, allowing face discrimination from the outside of the vehicle.
On the other hand, with the room lamp turned on, a reduced contrast of luminance can be obtained between the object of visual work and the environment. However, since the room lamp is located substantially at the center of the vehicle, light is not incident on the object of visual work adaptationally, resulting in a possible deterioration in visual power.
Further, since the lamp is arranged to the roof at its center portion (or in the vicinity of the center portion), the roof has a relatively light area in the vicinity of the lamp, and a relatively dark area at its portion distant from the lamp or its peripheral portion, resulting in a perception of narrowness of the cabin. This perception of narrowness of the cabin is also caused by the lamp which protrudes from the roof.
Furthermore, since the lamp directly provides light in the cabin, an illuminant of the lamp may be in a field of view of the driver after being reflected by an inside back mirror or a front window panel, or in a field of view of the passenger directly, causing glare and/or annoyance. Additionally, the illuminant of the lamp may directly be in a field of a driver or a passenger in a follower vehicle. Thus, during night run of the vehicle, the lamp is turned off in a general way so as to improve a forward sight and prevent a nuisance to the follower vehicle. In that event, the full darkness may cause the driver and the passenger, particularly, the latter, not only perception of narrowness but uneasiness in the cabin. In the full darkness, a switch, etc. are difficult to find, resulting in a decrease in operability and visibility thereof. Additionally, the driver or the passenger cannot feel a gorgeous atmosphere to be produced by high-grade material applying to interior members in the cabin.
It is, therefore, an object of the present invention to provide a lighting system for use in a vehicle cabin which provides an appropriate illumination in a vehicle cabin without glare and/or annoyance.